1. Field of the Invention
The present invention relates to a display panel employing a matrix of pixels made of antiferroelectric liquid crystal material.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2-173724 of Nippon Denso and Showa Shell Petroleum discloses a liquid crystal panel employing an antiferroelectric liquid crystal material. This panel realizes a wide view angle, a high-speed response, and a good multiplex property, and therefore, has been energetically studied.
FIG. 2 shows a display panel employing an antiferroelectric liquid crystal material according to a prior art. Polarizer plates 21a and 21b are arranged in a cross-Nicol relationship. An arrow 23a shows a polarization axis of polarizer plate 21a and an arrow 23b shows a polarization axis of polarizer plate 21b. A liquid crystal cell 22 is placed between the polarizer plates 21a and 21b so that the polarization axis of one of the polarizer plates 21a and 21b as shown by the arrow 23a or 23b is oriented in parallel with the major axis of an average molecule of the liquid crystal material when no electric field is applied. The cell 22 is black when no voltage is applied and is white when a voltage is applied. FIG. 3 shows a hysteresis curve indicating changes in the light transmittance of the cell 22 and voltages applied thereto. When the product of the width and height of a pulse applied to the cell 22 is above the threshold of the liquid crystal material, the liquid crystal material is put in a first stable state (a ferroelectric state) where the light transmittance of the liquid crystal material is saturated. When the polarity of a pulse whose product of the width and height is above the threshold of the liquid crystal material is inverted, the liquid crystal material is put in a second stable state (a ferroelectric state) where the light transmittance of the liquid crystal material is saturated. When the absolute value of the product of the width and height of the pulse applied to the liquid crystal material is below a threshold, the liquid crystal material is put in a third stable state (an antiferroelectric state).
The major axis of a liquid crystal molecule is oriented differently among the first to third stable states, and generally, an angle formed by this major axis between the first and third stable states is not equal to an angle formed by the same between the second and third stable states. Accordingly, when the polarization axis of one of the polarizer plates is in parallel with the major axis of an average liquid crystal molecule with no voltage like the prior art, the angle of this polarization axis from the major axis of a liquid crystal molecule changes between the first and second stable states. Consequently, the light transmittance of the liquid crystal panel fluctuates between the first and second stable states which displays different white colors and causes flickering.